The requirement for removing gas detectors from heated, corrosive industrial environments for the purposes of periodic calibration of the gas sensing device is a disadvantage associated with conventional in situ gas probes of the type described in copending patent application Ser. No. 247,368, entitled "Improved Gas Measuring Probe For Industrial Applications", filed Apr. 25, 1972 and U.S. Pat.No. 3,928,161 entitled "Improved Gas Measuring Probe For Industrial Applications", issued Dec. 23, 1975, the latter being a divisional application of the former, and both being assigned to the assignee of the present invention.
The tedious task of removing a gas detector from a heated and sometimes dangerous environment, coupled with the loss of the probe as an in situ gas monitoring device during the remote calibration activity clearly identifies a need for a practical technique to permit in situ calibration of gas detectors.